Integrated circuits are formed on semiconductor substrates, or wafers. The wafers are then sawed into microelectronic dies, or semiconductor chips, with each die carrying a respective integrated circuit. Each semiconductor chip is mounted to a package, or carrier substrate, which is often mounted to a motherboard.
“Power devices” are integrated circuits (IC) that are specifically designed to tolerate the high currents and voltages that are present in power applications, such as motion control, air bag deployment, and automotive fuel injector drivers. In particular applications, the power devices are required to block voltages in both a “positive” direction, where a voltage is applied to the drain side of a particular transistor with the source and the body shorted together and held at ground, and a “negative” direction, in which a negative voltage is applied to the drain side of the transistor with source and body held at ground. The ability to block both positive and negative voltages is known as “bi-directional” voltage blocking.
Traditionally, two separate transistors, placed “back-to-back,” are required to achieve bi-directional voltage blocking in power integrated circuit technologies. The need for two transistors drastically increases the size of the die and the final device. Bi-directional blocking can be achieved with one transistor if the source and body terminals are separated. However, traditional high-voltage and high-power devices, such as reduced surface field (RESURF) structures, for power ICs are designed with high-voltage blocking only on the drain side. As a result, the source side is only capable of lower voltage blocking.
Poor voltage blocking performance on the drain side is further compounded by the high concentration of dopants used in the various regions, and when a high voltage, such as between 5 and 7 volts, is applied to the source side, leakage current between the source and body terminal is dramatically increased due to the enhancement in electric field near the heavily doped junctions falling under the gate. Such current is often referred to as “hot carrier injection” (HCI) current, or “avalanche” current, and can significantly degrade the power device performance.
Accordingly, it is desirable to provide a RESURF structure with an increased breakdown voltage on the source side. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.